Display screen or portion thereof with transitional graphical user interface



1. Display screen or portion thereof with transitional graphical user interface

1.1 : Front

1.2 : Front

1.3 : Front

1.4 : Front

The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described; the outer perimeter shown in broken line in the drawings illustrates a display screen or portion thereof and forms no part: of the claimed design; the remaining broken lines in the drawings illustrate portions of the graphical user interface that form no part of the claimed design; fig. 1.1 is the image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design; fig. 1.2 is the second image thereof; fig. 1.3 is the third image thereof; and, fig. 1.4 is the fourth image thereof; the appearance of the transitional image sequentially transitions between the images shown in figs. 1.1 - 1.4 . The process or period in which one image transitions to another image forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 